The invention relates to a conveyor system, and particularly to foldable frames for side conveyor systems of screening units.
Screening units are used in many applications for the processing of various materials, such as sand, gravel, stone, soil and aggregate material. Such units comprise a screening device, and one or more conveyor systems on frames to carry the various types or grades of screened material to individual stockpiles. It is desirable that these screening units be movable from place to place within a worksite, and, indeed, from site to site. To achieve this one or more of the conveyor systems, particularly any side conveyor systems, are usually placed in a folded position prior to transport of the unit. If the unit is to be moved to a different site, it is important that the conveyor systems fold as close to the unit as possible, to meet the restrictions imposed on the width of vehicles travelling on public highways. This has become increasingly important as transportation of wide loads on roads and motorways has become more restrictive. Even if a unit is to remain in the same place within a site, it is desirable that the conveyor systems be placed in a folded position, to avoid inadvertent damage to them. Foldable conveyor systems and foldable frames for such systems have been developed, but many of these have experienced problems, for example in the ease of folding, or the strength of the frame and particularly in relation to the overall width or envelope of the folded screening unit.
Alternative mechanisms have been proposed that allow an upper section of a conveyor frame to fold such that the frame may be located above and in line with a body of the screening unit in the inoperative position. A disadvantage that has arisen with such arrangements is that relative lengths of sections of the frame may be restricted by the need to fold the frame over and along a body of the screening unit.